Etched crystalline hone



Aug. 29, 1944. s. BMLEY 2,356,910

' ETGHED CRYSTALLINE HONE Filed April 20, 1942 E TCHE'D QUARTZ SURFACE t Fig. 1

Fig.2

Fig.3

INVEN I'OR R/CHARD 5. BAILEY l Y @M MT 1 4 ATI'ORNE Patented Aug. 2 9, 1944 ETCHED CRYSTALLINE HONE Richard S. Bailey, Baltimore, Md., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application April 20, 1942, Serial No. 439,670

(Cl. 512l1) 1 Claim.

'This invention relates to abrading devices and more particularly to a honing device having a Working surface of improved characteristics and a process for the manufacture thereof.

At the present time there are two types of hone in'general use. In the first of these a quantity of small crystalline particles such as silicon carbide or aluminum oxide is mixed with a suitable binder. This mixture is next moulded to any desired shape and then either dried or fired, depending on the nature of the binder, to harden the product in its final form. The other form of hone is manufactured by pouring glass or any other similar homogeneous non-crystalline material into a mould where it is chilled and hardens to the final form of the product. In a number of cases it has been the practice to etch the surface of the class hone to increase its efficiency. As is well known, the above hones are characterised by the fact that a surface prepared in a manner insuring rapid removal of material does not provide a keen edge, and conversely, a surface capable of providing a keen edge, does not perform the operation quickly.

One of the principal objects of this invention is to provide a new and improved hone having the ability to sharpen a tool in a very short time and with little effort.

A further object of this invention is to provide a hone which will sharpen relatively soft materials rapidly without leaving a feather edge.

Still another object of this invention is to pro vide a hone capable of imparting an extremely sharp edge to any edged tool.

The above objects and advantages of the invention are realized by the use of a homogeneous crystalline substance for the material of the hone and etching the surface thereof with a suitable reagent, whereby the infinitesimal molecular layers project much after the form of stratified rock layers providing infinitesimal cutting teeth of very great efliciency.

Other objects and advantages of this invention will in part be disclosed and in part be obvious when the following specification is read in conjunction with the drawing in which:

Figure 1 is a view in perspective of a honing block utilizing the invention.

Figure 2 is a view in perspective of a honin block utilizing the invention and especially adapted to the sharpening of razor blades.

Figure 3 illustrates a honing instrument more economical in its use of the crystalline material and somewhat more convenient to use.

Referring to Figure 1, there is shown the block from an edged tool.

I having the flat upper surface 2. The block- I may be manufactured by sawing it intact out of a mother crystal of crystalline quartz, also des-, ignated as silicon dioxide.

After this initial step, the various surfaces and edges of the block are trued up by the use of grinding apparatus. The finished block may now be immersed in a solution of 48% commercial hydrofluoric acid for a period of ten hours. Upon the removal from the hydrofluoric acid, the crystal is dipped in a neutralizing solution and then thoroughly washed. The block I is now ready for use and it is utilized in the same way as previous hones having the same configuration; that is, the tool is moved relative to the block I back and forth over the surface 2, the angle of contact being regulated to secure the desired cutting edge angle.

It has been found that the above hone prepared in the manner outlined is far superior to previously available hones. It removes material much more quickly and at thesame time does not produce the feather edge'so often found in conjunction with the rapid removal of material It is believed that these unique properties are conferred by the presence of infinite numbers of very sharp cutting teeth, far sharper than those which may be produced by an artificial method known to man. These teeth are presumed to be formed by the projection of the molecular planes found within a crystal, the tooth-like structure being brought out by the use of an etching agent, hydrofluoric acid having been employed in the example just cited. It has been found that upon immersion of crystalline quartz in a hydrofluoric acid bath, the naturally fractured surfaces are substantially unaffected by the etching acid, while surfaces having artificially forced planes, such as those produced by cutting or grinding, are immediately attacked. For this reason, it is believed that damaged crystalline elements are much more susceptible to the action of an etching agent than those whose natural barrier walls remain intact. In the formation of the teeth above mentioned, it is believed that the damaged crystalline elements are removed from the working surfaces through the action of the etching agent, leaving the undamaged crystal elements projecting above the surface in the regular rows characteristic of the regular molecular orientation existing within all crystalline substances. These rows of projecting elements define knife-like cutting planes or teeth having a sharper cutting edge, i. e., one

of smaller radius, that can be fashioned by any human agency. Movement of an edged metal tool over the above surface results in very rapid removal of material due to the extreme sharpness of the cutting edges, while at the same time a very keen edge is provided due to the very fine structure of the working surface.

The block 3 of Figure 2 is similar in general form to the block I of Figure 1, the difference residing in the concave form of the working surface 4. As is well known, the presence of this concave surface renders it simple for the inexperienced user to sharpen a modern razor blade as it is only necessary to insert the blade in the hollow of the surface 4 and either rotate or reciprocate said blade using the thumb to impel the same.

Crystalline quartz of suitable quality is sometimes rather expensive and the complete hone of Figure 3 has therefore been evolved to effect a saving in the amount of quartz required. In this hone the body 5 with the attached handle '6, both of which may be made of wood or other suitable material, is provided with the receptacle I in which there may be cemented or otherwise suitably secured a honing block 8 manufactured in accordance with my invention. Most of the crystalline materials suitable for the construction of honing blocks are somewhat brittle and the construction just described permits the use of a very thin section of this material for the honing block 8 because of the reinforcement provided by the holder 5.

While I have confined my invention to the use of quartz for the purposes of discussion, it is obvious that any crystalline material having the desired hardness and available in sheets of the necessary size may be employed such as silicon carbide and other commercially available abrasives. Further, it is to be understood that where I have mentioned hones and honing operation, it is intended that grinding and abrading operations generally shall fall within the scope of this terminology. For example, a grinding wheel may easily be prepared in a manner similar to that above outlined, whereupon the advantages described may be realized in the grinding operation.

It will be obvious that many changes and modifications may be made in the invention without departing from the spirit thereof as expressed in the foregoing description and in the appended claim.

I claim:

In an abrading device, a block of crystalline quartz having an etched working surface.

RICHARD S. BAILEY. 

